Jacquard machine hook selecting device driven by a bistable element

ABSTRACT

A Jacquard machine for the positive lifting and lowering of the warp threads in a weaving machine, without the employment of harness cords and a method of operating the Jacquard machine. The Jacquard machine includes for each of a hook (6) a bistable element. The bistable element is formed as an elastically deformable rod (1) or an elastically deformable leaf spring. Periodically, a mechanical deformation loading acts on the bistable element which takes the bistable element into one of two stable states in dependence upon a slight initial deflection. An initialization device (8) brings about a slight deflection of the bistable element before the action of the mechanical deformation loading, in view of which it is ensured that the bistable element takes up a particular one of its two stable states. A hook drive device for the implementing of the mechanical deformation loading on the bistable elements (1) has a loading device (31) for exercising the deformation loading, in which the bistable elements (1) are mounted at least one side thereof.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The invention relates to a Jacquard machine which functions without theemployment of harness cords, and a method of operating the Jacquardmachine in accordance with the invention.

2. Discussion of the Prior Art

In a conventional Jacquard machine, hooks for raising and lowering thewarp threads of a weaving machine connected with the Jacquard machineare coupled with driven knives, or released from these knives, inaccordance with the weaving pattern to be woven. When the hooks areconnected with the driven knives, they carry out a shed-forming liftingand lowering movement. By means of a hook selection device particularhooks can be selected, in dependence upon the pattern to be woven, whichare separated from the driven knives and thus do not take part in thelifting and lowering movement. The registering of the pattern iseffected by means of a plurality of harness cords which permit aconnection through inter-engagement or form fitting or locking--apositive connection--between the hooks and the warp threads during thelowering movement. Respective warp threads in the register of thepattern are connected with respective hooks via harness cords. Toprovide the connection through force locking or action of a force--anon-positive connection--during the lowering movement, tension springsare in general provided at the end of the harness cords opposite to thehooks.

The employment of harness cords for controlling the lifting and loweringmovement of the warp threads is disadvantageous since the harness cordsare subject to great wear and the exchange of a torn harness cord duringthe operation of the weaving machine has the consequence that productionmust be brought to a halt for a long period of time.

In DE-PS 22 30 486, for the avoidance of this disadvantage, there isproposed a harnessless Jacquard machine. For control of each individualwarp thread there is provided a pressing device for coupling a hookprovided for each warp thread with two alternately moved lifting knives.The pressing device includes a selection device, which in correspondenceto the pattern to be woven selects individual hooks which do not takepart in the lifting and lowering of the lifting knives. The hooks areconnected, at their underside, the so-called hook floor, in each casewith a cord which is engaged with the warp thread to be raised or to belowered. Since the pressing device, in cooperation with the liftingknives, is however solely capable of delivering the lifting movement ofthe warp threads, there are provided at the lower ends of the cordstension springs for the lowering movement of the warp threads. DE-PS 2230 486 discloses the possibility of individual control of the warpthreads of the weaving machine and the replacement of the harness cordsby means of tear-resistant cords, but for the lowering movement of thewarp threads tensioning springs are however still necessary. The knownJacquard machine thus represents a Jacquard machine which during thelifting movement works in a positive manner and during the loweringmovement works in a non-positive manner.

From DE-AS 21 19 053 there is known a device which works harnessless,for shed formation in looms. For producing the lifting and loweringmovements of the warp threads there is provided for each warp thread awire or coil element which is connected with the warp thread concernedby means of a cord or rod. The wire or coil elements are arranged in astatic magnetic field and are subjected to an electric current. Inaccordance with the direction of the current the wire or coil elementsare deformed or deflected either upwardly or downwardly. The lifting orlowering movement produced by these means is transferred to the warpthreads by means of the cords or rods. Such an arrangement is howeverpractically realizable only with difficulty because of the necessaryhigh levels of current and magnetic field strength.

SUMMARY OF THE INVENTION

The object of the present invention is thus to provide a Jacquardmachine which works both in the lifting movement and in the loweringmovement in a positive manner and makes possible a rapid change of theposition of the warp threads. Further, it is the object of the presentinvention to provide a method of operating the Jacquard machine inaccordance with the invention.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1: a first exemplary embodiment of the hook control in the Jacquardmachine according to the invention;

FIG. 2: a second exemplary embodiment of the hook control in theJacquard machine in accordance with the invention;

FIG. 3A to FIG. 3E: diagrams for explanation of the hook control inaccordance with the invention in various movement phases;

FIG. 4: cascade arrangement for increasing the density of the hooks inthe Jacquard machine according to the invention;

FIG. 5: a third exemplary embodiment of the hook control in the Jacquardmachine according to the invention;

FIG. 6: a hook stroke/time diagram for explanation of the manner ofworking of the Jacquard machine in accordance with the invention.

FIG. 7 a transverse generally diagrammatic section through a firstfurther development of the hook drive device according to the invention,including hook selection device;

FIG. 8 a section similar to FIG. 7, shown on an enlarged scale, througha second further development of the invention;

FIG. 9 a section similar to FIG. 7, shown on an enlarged scale, througha third further development of the invention;

FIG. 10 a section through a fourth further development of the inventionwith the employment of an articulated lever in extended position;

FIG. 11 a section through a fourth further development of the inventionwith the employment of an articulated lever in folded position;

FIG. 12 a section through a fifth further development of the inventionwith employment of an articulated lever in extended position;

FIG. 13 a section through a fifth further development of the inventionwith employment of an articulated lever in folded position.

DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS

The invention is based on the concept that the employment of a bistableelement which has, under the effect of a mechanical deformation loading,a first stable positioning state in the lifted position of the hook anda second stable positioning state in the lowered position of the hookoffers simple control both of the lifting movement and also of thelowering movement of the hooks. Here and below, the term hook will beemployed for a movement element which ensures a positive connectionbetween a (hook) selection device and the warp thread to be controlled.The hook selection device thus has such an effect on the bistableelement that a particular one of the two positioning states for theselected hooks can be reliably attained. The hook may be connected withthe bistable element either directly or by means of a lifting device orthe like.

The bistable element is designed to be elastically deformable, inparticular in the shape of a rod or of a leaf spring. The mechanicaldeformation loading may thereby be effective by means of an axial orlongitudinally directed force component on the rod or the leaf spring.This can be brought about through the bringing together of two mountingpoints arranged in the end region of the rod or of the leaf spring, forexample by means of a cam or a hydraulic or pneumatic piston.

Further provided is a locking element which locks the bistable elementin one of its stable positioning states. During a locking time it isthus prevented that the associated hook takes part in the lifting andlowering movement. there is also further provided an unlocking elementthat releases the bistable element after a predetermined locking time.

An initializing device in dependence upon a corresponding control signalbrings about a directed initial deflection of the bistable element,whereby the bistable element, after being subjected to the effect of themechanical deformation loading (as initial condition when the Jacquardmachine is brought into operation) takes up a particular one of the twostable positioning states. The initialization device may be operated forexample hydraulically, pneumatically, electromagnetically orelectrostatically.

The Jacquard machine is operated in one embodiment as an open shedJacquard machine. Here, the bistable elements change directly betweenthe two stable positioning states and are locked in these states. Aftereach weft insertion of the weaving machine it is determined which hooksmust change their states, corresponding to the weaving pattern, for thenext weft insertion of the weaving machine. The change of thepositioning state of the bistable element is effected by means ofunlocking and correctly phased exercise of the mechanical deformationloading, so that the bistable element attains the respective otherpositioning state.

Pursuant to another embodiment, the Jacquard machine is operated as aclosed shed Jacquard machine. After each weft insertion of the weavingmachine, the bistable elements return to a neutral positioning state.After selection of the hooks to be raised and to be lowered, acorresponding initial deflection is exercised on each of the bistableelements, so that the bistable elements go over into a particular one ofthe two stable positioning states through exercise of the mechanicaldeformation loading.

The above-described Jacquard machine provides for each warp thread ofthe weaving machine a bistable element, in particular an elasticallydeformable road or an elastically deformable lead spring which isconnected with the associated warp thread in a positive and non-positivemanner via a respective hook. By means of an external mechanicaldeformation loading acting periodically on the bistable element, thebistable element is brought into one of its two stable positioningstates and the associated warp thread is correspondingly lowered orraised.

As a further development, mechanical deformation loading can be appliedto the bistable elements in a simple manner and after shed formation hasbeen achieved a reliable weft insertion into the weaving machine isensured. For the implementing of the mechanical deformation loading onthe bistable elements there is provided a loading device in which thebistable elements are mounted at least on one side. The loading deviceis coupled to a drive shaft in a non-positive but not in a positivemanner, so that the loading device is carried along by the drive shaftwhen the loading device is not deactivated. Such a deactivation of theloading device is effected by means of an arresting device when thehooks have attained their raised or lowered state, in order to ensure areliable weft insertion of the weaving machine, in particular tomaintain this state also for a plurality of insertions when this isnecessary. Thereby, the loading device has a loading lever which isconnected non-positively, in effect, through spring action, with thedrive shaft.

An arresting device is constituted as a block brake and in this case mayhave a pivotally mounted brake lever, which by way of suitable brakeblocks of a wear resistant material having a high coefficient friction,from a saw-tooth like engagement arrangement or the like exercise thenecessary braking force on appropriate parts of the loading device, inparticular by a loading lever, to deactivate the loading device. Thebrake blocks can here either be mounted directly on the brakelever--arranged on this brake lever--or can be set into the brake leverto avoid shearing off. The configuration as block brake is advantageousbecause upon an alteration of the swing path of the loading device noadjustment is needed; however, a secure retention in the brakingposition is significant.

The braking lever of the arresting device can be so pretensioned that abraking force is exercised on the loading device which is sufficient todeactivate the loading device. This has the advantage that the brakingforce can be applied without further energy-consuming drive means and,for example, upon failure of the operating supply to the machine, theloading device is automatically deactivated.

To release the arresting device, the block brake must be releasable in asuitable manner. This can be effected by means of a cam shaft or anelectromagnet. In the released condition, the arresting device can beheld by means of an electromagnet, for example engaging on the brakelever for so long until a renewed arresting has to be effected. Theelectromagnet can also be excited for a short period of time for thepurpose of control, and there must then be provision for a secureretention in the released condition, for example in accordance withclaim 31 a permanent magnet may be provided which alone, after controlby means of the electromagnets, is capable of retaining the brake lever.

Alternatively, the arresting device may be configured as anelectromagnetically, pneumatically or hydraulically actuable.. plungerwhich with appropriate actuation blocks the path of movement of theloading device.

An arresting device constituted as a block brake is further developed bymeans of an articulated lever which is its extended position deactivatesthe loading device by means of a brake block and in its folded positionreleases the loading device. For increasing the braking force there maybe further provided, in accordance with claim 34, a braking lever, theforce arm and the actuation arm of the braking lever having to beadapted to the braking force necessary for deactivating the loadingdevice.

For actuating the articulated lever there is employed an articulatedlever drive shaft arranged on one end of the articulated lever, whichdrive shaft--like the drive shaft for the loading device--carries outrocking movement in such a manner that the articulated lever istransformed between its extended and its folded position.

In order to fix the articulated lever in its extended position, and thusto arrest the loading device there is provided a suitable retainingdevice. This retaining device may be formed by means of an electromagnetwhich co-operates with a return device associated with the articulatedlever. Alternatively, the articulated lever may be so constituted thatits latches into its extended position. This can be attained by means ofoverextension of the articulated lever. To release the articulatedlever, and thus the deactivated loading device, there may be provided anelectromagnetically, pneumatically, hydraulically or similarly actuableplunger.

FIG. 1 shows a first exemplary embodiment of the hook control in theJacquard machine according to the present invention. There is shownsolely the arrangement for a single hook, which is present in a numbercorresponding to a number of hooks employed. The hook control has abistable element (in the present exemplary embodiment as elasticallydeformable rod 1). By means of a hydraulic apparatus 2a and 2b and aframework 3a and 3b, the rod 1 can be loaded with a pair of forcesacting in axial direction so that a mechanical deformation loading actsupon the rod 1. For this purpose the rod 1 is rotatably mounted in themounting points 4a and 4b on the framework 3a and 3b. The upper stablepositioning state of the rod is indicated in the Figure as a full line,while the lower stable positioning state is indicated in the Figure as abroken line. In the middle region of the deformable rod 1, a hook 6 ismounted at a mounting point 5 and connected with the rod 1 in a positiveand non-positive manner. At the underside of the hook 6 there is an eye7 for receiving a warp thread. It is, however, also possible to provideat the underside of the hook an attachment device for a cord or thelike, which provides the connection between the warp thread and the hook6.

After axial loading of the rod 1, this takes up either its upper stablepositioning state or its lower stable positioning state. Which of thetwo stable positioning states is selected depends substantially upon thecommencement conditions before the exercise of the axial loading on therod 1. For proper alteration of these initial conditions, aninitializing device 8 maybe provided which in the actual exemplaryembodiment is likewise formed as a hydraulic apparatus. The manner ofworking of the initialization device 8 will be discussed further below.For locking the elastically deformable rod 1 in its stable positioningstate there is provided a locking element 9 which is rotatable mountedon the framework 3a. On the side of the framework 3b the locking element9 has a catch end 10 into which the framework 3b latches after any oneof the two stable positioning states of the rod 1 has been attained.When the elastically deformable rod 1 is located in its upper stablepositioning state, the warp thread connected therewith via the hook 6 isalso in a raised state, while the warp thread is in a lowered state whenthe elastically deformable rod 1 takes up its lower stable positioningstate. During the locking of the rod 1 by means of the locking element10, the weaving shed of the weaving machine is consequently open.

If, for reason of the pattern to be woven, it is required that the warpthread connected with the hook 6 is to change from the raised into thelowered position, or vice versa, the locking condition is terminated bymeans of an unlocking element 11 which in the illustrated exemplaryembodiment is provided as a controllable electromagnet. Upon excitation,the electromagnet 11 effects a raising of the locking element 9 so thatthe framework 3a and 3b is free to move. Through the elastic deformationof the rod 1, it--together with the hook 6--is moved in the direction ofthe respective other stable positioning state. By means of the kineticenergy present in the neutral position, the dead point located there isovercome and the elastically deformable rod 1 is deformed at leastslightly in the direction of the respective other stable positioningstate. In this movement phase, the axial loading of the rod 1, effectedby means of the hydraulic apparatus 2a and 2b, is again applied wherebythe rod is finally completely deformed in such a manner that it takes upthe respective other stable positioning state.

Through this manner of movement, the hook 6 and the warp threadconnected therewith are transported from the raised into the loweredstate, or vice versa. After attainment of a new stable positioning stateof the elastically deformable rod 1, the framework 3b again latches intothe catch-like end 10 of the locking element 9, so far as theelectromagnet is not excited. The deformable rod 1 and the hook 6 remainso long in the raised or lowered state until this state must again bealtered in dependence upon the pattern to be woven.

The initializing device 8 serves, in the above-described operation ofthe Jacquard machine in accordance with the invention as an open shedJacquard machine, solely for the reliable attainment of the raised or ofthe lowered state when the machine is first brought into operation, andmay also be omitted. In the case of omission of the initializing device8 it is to be ensured, by means of a suitable pre-deformation of the rod1, that upon initiation of operations the rod initially takes up adefinite one of the two stable positioning states. For this basic orpre-deformation, the weight of the hook 6 may be sufficient. Finally,there is no need for all bistable elements--that is the rods 1--to takeup a predetermined positioning state upon initiation of operations, ifthereafter a void cycle, without weft insertion of the weaving machine,is effected, in which the initial positioning states of the bistableelements 1 are established.

Further, a sensor element or a pair of sensor elements 30a, 30b may beprovided in order to detect whether the elastically deformable rod 1 islocated in the raised or lowered positioning state. The sensor elements30a, 30b may be, for example, be constituted as electrical contacts oralternatively as proximity sensors working in a contactless manner. Inparticular when no initializing device 8 is employed, the sensorelements 30a, 30b are particularly advantageous since upon commencementof operations of the machine it can be reliably determined in which ofthe two stable positioning states each of the bistable elements, in thepresent exemplary embodiment formed as elastically deformable rods 1,are located. The positioning state of those elastically deformable rods1 which, with regard to the following weft insertion of the weavingmachine, are not located in the desired position can then, during thefollowing cycle of the applied deformation force, be taken into therespective other positioning state. The employment of the sensorelements 30a, 30b is also advantageous after the commencement ofoperations of the machine since it can be determined at any time whetherthe elastically deformable rods 1 and the hooks 6 are located in thepositioning states in accordance with the weaving pattern. If, forreason of a fault in operation, this is not the case for a particularhook 6, this fault can be removed in the next cycle and thus is notcarried through over the entire woven product.

In FIG. 2 there is illustrated a further exemplary embodiment of thehook control in the Jacquard machine in accordance with the presentinvention. Instead of an elastically deformable rod 1 or an elasticallydeformable leaf spring, the bistable element in the illustratedexemplary embodiment consists of a scissors-like framework 1a and 1bwhich engages rotatably into the framework 3a and 3b at the mountingpoints 4a and 4b. The mounting points 4a and 4b are, as in the exemplaryembodiment illustrated in FIG. 1, movable together and apart by means ofa hydraulic apparatus 2a and 2b. The device has further the locking andunlocking device 9-11 already described with reference to FIG. 1. Thescissors-like framework 1a and 1b has an upper, first stable positioningstate, illustrated in FIG. 2 by means of a solid line, and a second,lower stable positioning state, illustrated in FIG. 2 by means of abroken line. After the two mounting 4a and 4b are moved towards oneanother, the bistable element 1a, 1b takes up one of the two stablepositioning states. A purposive selection of a particular one of the twostable positioning states maybe effected either by means of thehydraulic or pneumatic piston 8 illustrated in FIG. 1 or, as illustratedin FIG. 2, by means of two electromagnets 8a and 8b. If a control pulseis applied to the electromagnet 8a, thus the electromagnet is excited,there is provided a downwardly directed initial deformation of thebistable element 1a and 1b so that upon bringing together of the twomounting points 4a and 4b the bistable element 1a and 1b moves into thelower stable positioning state. Conversely, the bistable element 1a, 1bgoes into the upper stable positioning state after bringing together ofthe two mounting points 4a and 4b if a corresponding control pulse isapplied to the electromagnet 8b, thus this electromagnet is excited (andthe other electromagnet 8a is de-excited).

A significant difference to the exemplary embodiment illustrated in FIG.1 consists, for the exemplary embodiment illustrated in FIG. 2, in thatthe elastic deformation energy of the bistable element cannot beexploited for changing over the deformation loading states. However, theelastic deformation of the warp thread can be exploited in acorresponding manner. Further, the pattern of movement described withreference to FIG. 1 can be attained in that at least upon lifting of thehook 6 during a first movement phase the mounts 4a, 4b are moved apartfrom one another by means of active operation of the thrust apparatus2a, 2b, while after passage through the dead point, these are againbrought towards one another.

It is to be emphasized that the exemplary embodiments illustrated inFIG. 1 and FIG. 2 can be modified or varied in many respects inaccordance with the inventive concept. In particular, a section of theelastically deformable bistable element may be formed to bemagnetostrictive or electrostrictive, so that the effect of a magneticor electric field brings about the necessary initial deformation. Thethrust apparatus 2a, 2b need not necessarily be hydraulic or pneumatic.The periodic exercise of mechanical deformation loading on the bistableelement can also be effected, for example by means of a gear or a cam ofa driven shaft. In particular, it is also possible to provide one of themounting points 4a or 4b fixed in position and displace only the othermounting point upon application of the deformation force. Likewise, itis possible to mount the bistable element fixedly or rotatablydisplaceably at at least two points. The locking element 9 canalternatively lock each of the two ends of the bistable elementseparately and independently of one another. The unlocking element can,of course also be formed to be mechanically controllable in classicmanner.

With reference to FIGS. 3A to 3E the operation of the Jacquard machinein accordance with the invention as a closed shed Jacquard machine willbe described. It is assumed that the elastically deformable rod 1, whichin the present exemplary embodiment forms the bistable element, returnsto a neutral initial position illustrated in FIG. 3A after each weftinsertion of the weaving machine. The neutral condition of theelastically deformable rod 1 corresponds to the closed condition of theweaving shed of the weaving machine, e.g. all warp threads have in theweaving machine an approximately equal level. After determination ofwhich of the warp threads are to be lifted for the next weft insertionof the weaving machine, and which warp threads are to be lowered,corresponding control signals are transferred to all initializationdevices 8 which are provided for all hook control devices. In thepresent exemplary embodiment, the initialization device 8 is formed ashydraulic or pneumatic piston. The initialization device effects aslight initial deflection which can deform the bistable element 1 in thedirection of the lowered positioning state, as shown in FIG. 3B, or inthe direction of the raised positioning state, as shown with referenceto FIG. 3D. The deformation force thereby necessary may be minimal. Itis solely required that by means of the subsequent action of themechanical deformation loading, which is generated in the illustratedexemplary embodiment by means of the hydraulic or pneumatic thrustapparatus 2a, 2b the bistable element, e.g. the rod 1 moves into aparticular positioning state unambiguously determined by means of theinitial deflection.

The complete deformation of the bistable element 1, up to attainment ofone of the stable positioning states, is represented in FIG. 3C and 3Erespectively for the upper and the lower positioning state. Thedeformation loading from the thrust apparatus 2a, 2b is transferred tothe elastically deformable rod 1 by means of the framework 3a, 3b. Afterending of the exercise of the elastic deformation loading, the elasticdeformable rod 1 again relaxes into the neutral condition illustrated inFIG. 3A. The described procedure is periodically repeated after eachweft insertion of the weaving machine.

FIG. 4 shows a cascade-like arrangement of the hook control devices 13-1and 13-5 in accordance with the invention.

In the tensioning direction of the warp threads 12 several (in theillustrated exemplary embodiment 5) hooks 6-1 to 6-5 are provided intowhich there engage respective different warp threads 12. The associatedhook control devices 13-1 to 13-5 are arranged one above the other.Through the elimination of the harness cords from the Jacquard machinein accordance with the invention the space provided in conventionalJacquard machines for spanning the harness cords is now available forthe arrangement of the hook control devices in accordance with theinvention above one another and alongside one another. The exemplaryarrangement illustrated in FIG. 4 refers to the exemplary embodiment ofthe hook control device 13 illustrated in FIG. 3. The individual hookcontrol devices 13-1 to 13-5 work as explained with reference to FIG. 3Ato 3E. The individual control devices 13-1 to 13-5 may, however, also beformed as explained with reference to FIGS. 1 and 2. The individual hookcontrol devices 13-1 to 13-5 function as explained with reference toFIGS. 1 and 2 or FIGS. 3A to 3E.

By means of the hooks 6-1 to 6-5, arranged offset in the deflectiondirection of the warp threads 12, and the arrangement of the individualhook control devices 13-1 to 13-5 one above another, the effective spacerequirement of an individual hook control device in the weft directionof the weaving machine, e.g. perpendicular to the tensioning directionof the warp threads 12, can be substantially reduced. In the weftdirection of the weaving machine, the arrangement illustrated in FIG. 4may be formed with offset repeats as often as necessary in order to beable to individually control each individual warp thread. By means ofbroken lines there is illustrated the lower stable positioning state ofthe bistable elements 1-1 to 1-5 and the lowered state of the hooks 6-1to 6-5 and of the warp threads 12. When all warp threads 12 are in theraised or lowered state, the weaving shed 14 is formed between them.

FIG. 5 shows a further exemplary embodiment of the hook control devicein accordance with the invention. Differently from the forms ofembodiment illustrated up to now, the hook 6 is not directly connectedwith the bistable element 1 but is connected non-positively with thebistable element, here again a rod 1, by means of a lever device 22which is rotatably mounted at a position 23. The raised condition of thehook 6 and the corresponding position of the rod 1 and of the leverdevice 22 is indicated in FIG. 5 by means of broken lines. Alsodifferently from the forms of embodiment illustrated above, themechanical deformation loading acting on the rod 1 is periodicallyapplied by means of a cam 21 sitting on a driven shaft 20. The end ofthe rod 1 away from the cam 21 is mounted in a fixed location. By meansof the electromagnets 8a and 8b respective particular ones of the twostable positioning states of the rod 1, as described above withreference to FIG. 2, can be reliably selected. Before action of the cam21 on the rod 1, the rod experiences an initial deflection either in thedirection of the raised or in the direction of the lowered positioningstate. The employment of the lever device 22 in the illustratedexemplary embodiment exhibits the advantage that the hook stroke or theforce for lifting and lowering the hook 6 may be varied.

FIG. 6 shows the temporal development of the hook stroke for differingmanners of operation of the Jacquard machine in accordance with theinvention. It is assumed that after commencement of operations of theJacquard machine initially every second hook is raised and the otherhooks are lowered. Then, those hooks are selected which upon the nextweft insertion of the weaving machine must have the state just takenup--in FIG. 6, the raised state. The temporal development of thepositioning of these hooks is indicated by means of a chain line. Theother, previously raised hooks, are lowered during the time period t₁ tot₃. Within a predetermined temporal tolerance range around the timepoint t₃, the weft insertion of the weaving machine may be effected.Thereafter, it is again determined which hooks--with regard to the nextsubsequent weft insertion of the weaving machine--are already in thecorrect state. These hooks remain during the time period t₃ to t₅ in theraised or lowered state, while the other hooks change their positioningstate during this time period. The next weft insertion of the weavingmachine takes place in a temporal tolerance range around the time pointt₅, etc. This applies also, in inverse fashion, for the hooks which arelowered in the initial step.

A section through a first further development of the hook drive devicein accordance with the invention is shown in FIG. 7. Furthermore, therecan be seen from the Figure further significant elements of the proposedJacquard machine. As already explained, the Jacquard machine has amechanically deformable bistable element 1 which in the illustratedfurther development is formed as an elastic deformable rod. Thisbistable element 1 can however also have other configurations, e.g. inthe form of a leaf spring. For each warp thread of the weaving machinethere is provided such a bistable element which in each case isconnected with the warp thread 12 by means of a merely schematicallyrepresented hook 6 and an eye 7. Through deformation of the bistableelement 1, either into the lowered state 1a or into the raised state 1b,the associated warp thread 12 is either lowered or raised, in order toform a suitable weaving shed.

The bistable element 1 is part of a hook drive device of the Jacquardmachine. For deformation of the bistable element 1, the hook drivedevice further has a loading device 31 to be explained below, by meansof which the bistable element is acted upon with a substantially axiallyacting elastic deformation loading.

The Jacquard machine has further a hook detection device 30 in order todetect the lowered state 1a or the raised state 1b of the bistableelement, separately for each bistable element. In the furtherdevelopment according to FIG. 7, the hook detection device 30 isschematically represented by means of two sensor element arrangements30a, 30a' and 30b, 30b', e.g. hall effect sensors, piezo elements, orthe like. When the bistable element 1 concerned is in its lowered state,illustrated by solid lines, the sensor element parts 30b and 30b' lieopposite one another so that this state can be detected. Agreement withthe pattern data can be determined and the necessity for a controlaction checked. This is in particular necessary following aninitialization operation. In similar manner, the held state is detectedby means of the sensor element parts 30a and 30a'.

For the application of the mechanical deformation loading, the loadingdevice 31 has a loading lever 32. In the loading lever 32, there areprovided mounting elements 33 for the mounting of the bistableelement 1. The loading device can receive either several or all bistableelements 1 of the Jacquard machine, there being expediently provided aseparate loading lever 32 for each bistable element 1, whereby theloading levers are arranged--in the width extension of the Jacquardmachine, which is not shown--offset one next to the other, or can be soarranged. The loading lever 32 is coupled to the drive shaft 34 in anon-positive but not in a positive manner and is rotatably mounted on anaxis 39 arranged concentrically to the drive shaft 34. A correspondingcoupling between the loading lever 32 and the drive shaft 34 can beeffected either in a simple manner by means of frictional linkage oradvantageously via a coupling spring, in particular a leaf spring. Forreducing the friction, an open hole 35 (a depression) may be provided.The drive shaft 34 carries out an oscillating or rocking movement,indicated by the arrow 36, in which the loading lever 32 takes part, sofar as an arresting device--to be described below--is not actuated. Inorder to make possible the movement of the drive shaft 32 also when theloading lever 32 is deactivated by means of the arresting device to bedescribed below, this arresting device has, in the illustrateddevelopment, a recess 37 in which the lower end 38 of the loading lever32 is freely moveable.

Furthermore, the hook drive device according to the invention has anarresting device in order that the loading device--in the illustrateddevelopment the loading lever 32--can be deactivated when the bistableelements 1 have attained either their raised state 1b or lowered state1a. In relation thereto, the following differing further developmentswill be described.

The further development illustrated in FIG. 7 has, as a particularlysimple solution, a plunger 41 actuable by means of an electromagnet 40,which plunger blocks the path of movement of the loading lever 32 at asuitable point. The bistable elements 1 then remain for so long in theirloaded state 1a or 1b until the plunger 41 is removed from the path ofmovement of the loading lever 32 by means of the electromagnet 40 andthe loading lever 32 is carried along by the drive shaft 31 anew. Ofcourse, the plunger 41 can be actuated, instead of electromagnetically,also pneumatically or hydraulically or in other suitable manner. Inorder to retract the plunger 41, a return spring 42 may be provided.

FIG. 8 shows a further development of the arresting device. Thearresting device in accordance with FIG. 8 has a braking lever 51rotatably mounted on an axis 50. The braking lever 51 is, for example bymeans of a merely schematically illustrated tensioning spring 52,pretensioned in such a manner that the braking lever 51 exercises via abrake block 53, on the loading lever 52, a force sufficient todeactivate the loading lever 32. By means of the braking lever 51, asuitable braking force amplification is attained. In order to againrelease the loading lever 32, after ending of the arresting procedure,there is necessary a suitable device for lifting up the braking lever51. For this purpose there is provided, in the development according toFIG. 8, a cam shaft 54 which rotates around an axis 55 and does thissynchronously with the rocking movement. The cam 56 of the cam shaft 54lifts the braking lever 51, for releasing the loading lever 32, up sofar that the brake block 53 is brought out of engagement with theloading lever 32. For holding the loading lever 51 in the raisedposition a corresponding holding device is needed. This can be realizedin a simple manner by means of an electromagnet 57 which can co-operatewith a permanent magnet 58 arranged on the opposite side of the brakinglever 51 in order to make possible a holding of the released (lifted)braking lever 51 in this position without the consumption of energy.Upon "offering", e.g. by means of the cam shaft 54, two conditions arethus possible: if the electromagnet 57 is excited it has a magneticfield of the same polarity (as the permanent magnet 58), for whichreason no attraction but rather repulsion, takes place; if theelectromagnet is not excited (de-excited), then the permanent magnet 58alone holds the braking lever 51, in a currentless manner, against thereturn force (spring 52) in the open position. In a simplified form ofconfiguration, instead of such a permanent magnet on the side of thebraking lever 51 opposite to the electromagnet 57 there can be provideda region with a material of high magnetic permeability. The release ofthe braking lever 51 from the electromagnet 57 is effected by means ofthe spring force exercised by the tension spring 52 and/or by reversalof the current direction of the electromagnet 57.

An arrangement according to the rule of "kinematic reversal" is likewisepossible.

There is to be provided for the brake block 53 preferably a material oflowest possible wear with a high coefficient of friction. The brakeblock 53 may either, as in the illustrated further development, beattached to the underside of the braking lever 51 or, alternatively, tothe overside of the loading lever 32. There may also be provided asaw-tooth like engagement arrangement with a brake block cushion, as isschematically indicated in FIG. 2 on the corresponding surface on theloading lever 32.

The further development illustrated in FIG. 9 corresponds to thegreatest extent to the development described above with reference toFIG. 7. Differently from FIG. 8, in the development according to FIG. 9,two brake blocks 53a and 53b arranged one behind the other are provided.The brake blocks, formed as segments of spheres, can be pressed intocorresponding recesses 59a and 59b so that a rapid and simpleinstallation of these consumables is ensured. By means of the secureseating of the brake blocks 53a and 53b a shearing off of the same uponoperation of the device is largely avoided.

The further developments to be described below, illustrated in FIG. 10to 13, differ from the above-described further development in that anarticulated lever 60 is employed as a further configuration of thearresting device formed as brake block.

The loading device 31 illustrated in FIG. 10 has the elements alreadydescribed with reference to FIGS. 7 to 9, namely a loading lever 32,mountings 33 for the bistable elements 1 and a drive shaft 34 whichcarries out a rocking movement. Reference is therefore made to the abovedescription.

The articulated lever 60 consists of the articulated lever elements 60aand 60b, whereby the lower articulated lever element 60b may beelastically formed, e.g. as U-shaped leaf spring. The articulated leverelements 60a and 60b are mounted rotatably with respect one to the otherin the mounting element 60c. The upper articulated lever element 60astands in engagement with the braking lever 51 and is likewise pivotallyconnected with this braking lever via the bearing element 61. For itspart, the braking lever 51 is pivotally mounted on the axis 50 and actsby means of the brake block 53 on the loading lever 32. In the conditionof the arresting device with extended articulated lever 60 (unstablecondition), illustrated in FIG. 10, a braking force is effected by meansof the braking lever 51 and the brake block 53 on the loading lever 32which arrests this lever. In the condition of the arresting deviceillustrated in FIG. 11, the articulated lever 60 is in contrast folded(stable condition) and, via the braking lever 51, lifts the brake block53 up so far that the loading lever 32 is released. In the releasedcondition according to FIG. 11, the loading lever 32 is thus carriedalong by the drive shaft 34 as described above and carries out theabove-described rocking movement, which is indicated in FIG. 11 by meansof broken lines.

In order to take the articulated lever 60 from its extended conditionshown in FIG. 10 into the folded condition shown in FIG. 11, and viceversa, there is provided at the lower end of the lower articulated leverelement 60b an articulated lever drive shaft 62 which carries out arocking movement which is synchronous with the rocking movement of thedrive shaft 34. By means of the rocking movement of the articulatedlever drive shaft 62, the articulated lever is in each case taken fromits folded condition illustrated in FIG. 11 into the extended conditionillustrated in FIG. 10. Whether the articulated lever 60 is, conversely,taken from the extended condition illustrated in FIG. 10 into the foldedcondition illustrated in FIG. 11, depends upon whether a holding device70 is activated. By means of the holding device 70, the articulatedlever 60 is held in its extended condition for so long as the arrestingof the loading lever 32 is necessary. For releasing the loading lever 32the articulated lever 60 is released by means of deactivation of theholding device 70, so that the brake block 53 of the braking lever 51goes out of engagement with the loading lever 32. The holding device 70must exercise a sufficiently high holding force on the articulated lever60 so that the deformation of the lower articulated lever element60b--formed elastically in the illustrated development--is not able torelease the articulated lever 60 in the course of the rocking movementof the articulated lever drive shaft 32.

The holding device 70 may be formed, corresponding to the furtherdevelopment in accordance with FIG. 10 and 11, in a simple manner as anelectromagnet 71.

Another further development of the holding device for the articulatedlever 60 is illustrated in FIGS. 12 and 13. The further developmentaccording to FIGS. 12 and 13 is to the largest extent identical with thedevelopment described above with reference to FIGS. 10 and 11, so that adetailed description is not needed. The fixing of the articulated lever60 in the extended condition illustrated in FIG. 12 is, in thisdevelopment, attained in that the articulated lever 60 is slightlyoverextended and thus fixed in this condition. A corresponding fixingcould alternatively be realized by means of a latching mechanism. Forreleasing the articulated lever 60, the holding device 70 has, in theillustrated development, a plunger 73 actuable by means of anelectromagnet 72, which plunger upon actuation presses against thearticulated lever 60 and releases it. The actuation of the plunger 73could, of course, be effected in similar manner pneumatically orhydraulically. Also, corresponding to FIGS. 8 and 9, an electromagnetcould co-operate with a permanent magnet.

The movement of the articulated lever drive shaft 62 during the rockingmovement of the articulated lever drive shaft 62, with the articulatedlever 60 fixed in the extended position, is indicated in FIGS. 10 and 12by means of broken lines. There may be provided in a carrier 63 on thearticulated lever drive shaft 62 a permanent magnet 64 which reliablylifts the lower articulated lever element 60b--co-operatingtherewith--from the holding device 70 upon the rocking movement of thearticulated lever drive shaft 62 when the holding device is notcontrolled for holding the articulated lever 60 in the extendedcondition. The carrier 63 ensures that upon the rocking movement, an"offering" of the articulated lever to the holding device 70 takesplace.

The above-described hook drive device is suitable, as can beappreciated, admirably for the drive of a Jacquard machine which worksin accordance with the principle of FIGS. 1 to 6. It can also beprovided in a double-sided manner at both ends of the bistableelement 1. Further, instead of electromagnetic components, othercontrollable components, e.g. piezo elements may be provided. Ofsignificance is the control function.

Alternatively, the Jacquard machine can also work as quasi-closed shedJacquard machine. In this case, each hook which does not need to changeits state does not remain in the raised or lowered state, but are so farlowered or raised that the neutral positioning state of the bistableelement is approximately obtained. There remains, however, a certaindeflection in the direction of the previously assumed positioning state.Those hooks which are to change their positioning states overstephowever the neutral state of the bistable element and receive a slightdeflection in the direction of the other stable state of the bistableelement. As soon as the mechanical deformation loading again has effecton the bistable element, those hooks which have not stepped beyond theneutral state of the bistable element are returned into the previouspositioning state, while those hooks which have stepped beyond theneutral state of the bistable element before exercise of the mechanicaldeformation loading are in each case taken into the respective otherpositioning state. The advantage of this manner of operation of theJacquard machine is to be seen in that at a time point t2, t4 etc. ineach case approximately closed shed position of the weaving shed can beattained which may be of significance for the quality of the wovenproduct.

I claim:
 1. Jacquard machine having hooks (6) for raising and loweringwarp threads (12) in a weaving machine, a hook drive device (1, 2a, 2b;1, 20, 21) for selectively imparting a lifting or lowering movement tothe hooks (b); and a hook selection device (8, 9, 11), which selectsparticular ones of the hooks (6) in order to hold the warp threads (12)connected with said selected hooks (b) characterized that,the hook drivedevice (1, 2a, 2b; 1, 20, 21) includes for each said hook (6) deformablebistable element (1) driving the hook in a positive manner, saiddeformable bistable element responsive to an external mechanical loadingacting periodically on the deformable bistable element (1) alternativelytakes up a first stable positioning state which corresponds to a raisedstate of the hook (6), or a second stable positioning state, whichcorresponds to a lowered state of the hook (6), and means causing thehook selection device (9-11) to impart a mechanical deformation to thebistable deformable element (1) to produce after each period of themechanical loading a specific one of the two stable positioningconditions for the selected hooks (b), and a neutral positioningcondition in the absence of any mechanical loading.
 2. Jacquard machineaccording to claim 1, characterized in that,the hooks (6) are in directconnection with the associated deformable elements (1) and the firststable positioning state of each deformable element (1) takes up aposition which is raised relative to the second stable positioningstate.
 3. Jacquard machine according to claim 1 or 2, characterized inthat,the hooks (6) are connected in a non-positive manner with therespective associated deformable elements by means of a lever device(22, 23).
 4. Jacquard machine according to claim 1, characterized inthat,each said deformable element (1) is elastically deformable. 5.Jacquard machine according to claim 4, characterized in that,each saiddeformable element (1) is formed as and elastically deformable rod, oras an elastically deformable leaf spring.
 6. Jacquard machine accordingto claim 5, characterized in that, a force generating component isprovided for bistably deforming the elastically deformable rod or theelastically deformable leaf spring in two directions transverse to theaxis or longitudinal direction of the rod or leaf spring.
 7. Jacquardmachine according to claim 5, characterized in that, the elasticallydeformable rod or the elastically deformable leaf spring is mounted atpoints in end regions thereof connected at least to one side tomechanical loading means, and the associated hook (6) is connected withthe middle region of the rod or the leaf spring in a non-positivemanner.
 8. Jacquard machine according to claim 7, characterized inthat,the rod or the leaf spring is rotatably or pivotably mounted in itsend regions and the deformation is achieved by means of the movingtogether of the two mounting points (4a, 4b).
 9. Jacquard machineaccording to claim 7 characterized in that,the hook selection device hasa locking element (9) which so locks the deformable element (1) in thefirst and/or second stable position state that it remains in therelevant positioning state also after the action of the mechanicalloading.
 10. Jacquard machine according to claim 9 characterized inthat,the locking element (9) fixes the mounting points (4a, 4b) of therod or the leaf spring at a fixed spacing from one another after theyhave been moved together.
 11. Jacquard machine according to claim 9characterized in that,the hook selection device further has an unlockingelement (10) which unlocks the locking element (9), in dependence upon acontrol signal, and thus releases the deformable element (1). 12.Jacquard machine according to claim 11 characterized in that,theunlocking element (11) is electrically actuable, by means of anelectromagnet.
 13. Jacquard machine according to claim 12 characterizedin that,an initializing device (8; 8a, 8b) is provided which, independence upon a control signal, brings about a directed initialdisplacement of the deformable element out of its neutral positioningstate in such a manner that the deformable element (1) after action ofthe mechanical loading takes up a particular one of the two stablepositioning states.
 14. Jacquard machine according to claim 13,characterized in that,the initialization device is formed by means ofone, or by means of a pair of electromagnets (8a, 8b) in order to applya force component to the deformable element, after application of anelectrical control signal, in such a manner that a corresponding initialdeflection is brought about.
 15. Jacquard machine according to claim 13,characterized in that,the initialization device has a hydraulic orpneumatic piston (8) which is connected with the deformable element andafter being acted upon with a working pressure or working vacuum bringsabout the initial deflection of the deformable element.
 16. Jacquardmachine according to claim 13, characterized in that,the deformableelement (1) has, at least in one portion thereof, magnetostrictive orelectrostrictive properties and the initial deflection is brought aboutby means of action of a magnetic or electric field on the relevantsection of the deformable element (1).
 17. Jacquard machine according toclaim 1 characterized in that,the periodical mechanical loading isbrought about by means of a cam sitting on a driven shaft or by means ofa hydraulic or pneumatic piston periodically acted upon with a workingpressure.
 18. Jacquard machine according to claim 1, characterized inthat,in the vicinity of the deformable element there are provided sensorelements (30a, 30b, 30a', 30b') for detecting the positioning state ofthe deformable element (1).
 19. Jacquard machine according to claim 1,characterized in that,the deformable element is formed as ascissors-like framework (1a, 1b; FIG. 2) which bistably kinks outwardlyin response to an axial deformation loading.
 20. Jacquard machineaccording to claim 1, characterized in that,a plurality of hook drivedevices (13-1, 13-2, 13-3, 13-4, 13-5) are arranged in a cascade-likemanner for operating a plurality of hooks (6-1, 6-2, 6-3, 6-4, 6-5)arranged offset in the direction of the warp threads.
 21. Hook drivedevice for a Jacquard machine according to claim 1 characterized by, aloading device (31) for exercising a mechanical loading on thedeformable bistable element (1) which is mounted in the loading device(31), a drive shaft (34) which carries out a rocking movement, saiddrive shaft being load-transmissively connected with the loading device(31), the loading device (31) having a pivotably mounted loading lever(32) which is load-transmissively connected with the drive shaft (34),and an arresting device (40-42; 50-59; 50-73) for deactivating theloading device (31) when the hooks (6) have reached their raised orlowered state.
 22. Hook drive device according to claim 21,characterized in that,the arresting device (50-73) is formed as a blockbrake.
 23. Hook drive device according to claim 22, characterized inthat,the arresting device (50-73) has a pivotably mounted braking lever(51) which acts upon one or more brake blocks (53; 53a, 53b) of a wearresistant material having high coefficient of friction, out of asaw-tooth like engagement arrangement or the like.
 24. Hook drive deviceaccording to claim 23, characterized in that,the brake blocks (53; 53a,53b) sit (FIG. 2) on the brake lever (51), arranged thereon, or are setinto the brake lever (FIG. 3).
 25. Hook drive device according to claim23, characterized in that,the brake lever (51) is so pretensioned, inparticular by means of a spring (52), that there is exercised upon theloading device (31) a braking force sufficient to deactivate the same.26. Hook drive device according to claim 21 characterized in that,thearresting effect exercised by the arresting device (50-53) is releasableby means of a cam shaft (54) and/or an electromagnet (57).
 27. Hookdrive device according to claim 26, characterized in that,the arrestingdevice (50-53) is held in the released condition by means of anelectromagnet (57) at least for a short period of time for purpose ofthe exercise of control.
 28. Hook drive device according to claim 27, inthat for holding the arresting device (50-53) after the exercise ofcontrol in the released condition there is provided a permanent magnet(58) which can alone hold the arresting device against a return of theloading device (31).
 29. Hook drive device according to claim 21,characterized in that,the arresting device (40-42) has a plunger (41)actuable electromagnetically, pneumatically, hydraulically or by likemeans, which plunger blocks the path of movement of the loading device(31).
 30. Hook drive device according to claim 22, characterized inthat,the arresting device (50-73) has an articulated lever (60) which inan extended condition (FIG. 10, 12) deactivates the loading device (31)by means of a brake block (53) operatively connected to said lever (60)and in a folded condition (FIG. 11, 13) release he loading device (31).31. Hook drive device according to claim 30, characterized in that,abrake lever (51) is provided by means of which the articulated lever(60) acts upon the brake block (53).
 32. Hook drive device according toclaim 30 characterized in that,an articulated lever drive shaft (62) isprovided at one end of the articulated lever (60), which drive shaft soeffects a rocking movement that the articulated lever (60) can betransformed between its extended and folded condition.
 33. Hook drivedevice according to claim 30 characterized in that,a holding device (70)is provided which fixes the articulated lever (60) in its extendedposition in order to deactivate the loading device (31) by means of thebrake block (53).
 34. Hook drive device according to claim 33,characterized in that,the holding device (70) has an electromagnet (71).35. Hook drive device according to claim 34, characterized in that,theelectromagnet (71) of the holding device (70) cooperates with a returndevice associated with the articulated lever (60), such as a spring or apermanent magnet (64) provided on the articulated lever drive shaft(62).
 36. Hook drive device according to claim 30, characterized inthat, the articulated lever (6) is overextended in the extendedcondition so as to latch the loading device in this position, and can bereleased from this position by operating structure consisting of aplunger (73) which is selectively actuable electromagnetically,pneumatically, and hydraulically.
 37. Method of operating a Jacquardmachine as an open shed Jacquard machine, having hooks (6) for raisingand lowering warp threads (12) in a weaving machine, a hook drive device(1, 2a, 2b; 1, 20, 21) having deformable bistable elements forselectively imparting a lifting or lowering movement to the hoods (6);and a hook selection device (8, 9, 11), which selects particular ones ofthe hooks (b) in order to hold the warp threads (12) connected with theselected said hooks (6) in a raised or lowered state; comprising thefollowing steps:a) applying a mechanical loading on the deformablebistable elements (1) so that the deformable bistable elements (1) takeup one of two stable positioning states, the hooks (6) consequently takeup either the raised or the lowered state and the weaving shed of theweaving machine is opened; b) locking the deformable bistable elements(1); c) determining for each hook (6) whether the present raised orlowered state of the hook (6) corresponds to the state needed for thenext weft insertion of the weaving machine in accordance with theweaving pattern, and selecting those deformable bistable elements (1)whose associated hooks (6) are not present in the required state; d)changing the state of the deformable bistable elements (1) selected instep c), by means of unlocking the selected deformable bistable elements(1) so as to relax these selected bistable elements; correctly phasingthe application of the mechanical loading, in order to deform thedeformable bistable elements (1) anew, in the direction of therespective other stable positioning state, and locking the applicableselected deformable bistable elements (1) after attainment of therespective other stable positioning state, and periodically repeatingsteps c) and d) after each weft insertion of the weaving machine. 38.Method according to claim 37, wherein the warp threads (12) are guidedby the hooks (6) to cause the threads to take up an approximately closedshed position prior to each weft insertion of the weaving machine. 39.Method of operating a Jacquard machine as a closed shed Jacquardmachine, having hooks (6) for raising and lowering warp threads (12) ina weaving machine, a hook drive device (1, 2a, 2b; 1, 20, 21) includingdeformable bistable elements for selectively imparting a lifting orlowering movement to the hooks (6); and a hook selection device (8, 9,11), which selects particular ones of the hooks (6) in order to hold thewarp threads (12) connected with the selected said hooks (6) in a raisedor lowered state; comprising the following steps:a) bringing thedeformable bistable elements (1) into a neutral positioning state inwhich the hooks (6) take up an intermediate state lying between theraised and lowered state, and in which the weaving shed of the weavingmachine is closed; b) determining which of the hooks (6) must be presentin the raised state and which of the hooks must be present in thelowered state upon the next weft insertion of the weaving machine incorrespondence with a specified weaving pattern, and selection of thehooks to be raised and to be lowered; c) bringing about an initialdeflection for each of the deformable bistable elements (1) in thedirection of the first positioning state for the hooks (6) which are tobe raised and in the direction of the second positioning state for thehooks (6) which are to be lowered; d) exercising a mechanical loading onall said deformable bistable elements (1) so that, in dependence uponthe initial deflection, said deformable bistable elements take up one ofthe two stable positioning states; and e) effecting periodic repetitionof steps a) to d) after each weft insertion of the weaving machine.